Subject: Re: [PATCH rc v2 1/5] iommu/arm-smmu-v3: Add arm_smmu_adopt_strtab() for kdump

From: Jason Gunthorpe <[email-masked]>
Date: Fri, 24 Apr 2026 17:50:31 -0300

On Fri, Apr 24, 2026 at 11:33:16AM -0700, Nicolin Chen wrote:
> On Fri, Apr 24, 2026 at 01:56:13PM -0300, Jason Gunthorpe wrote:
> > On Wed, Apr 15, 2026 at 02:17:36PM -0700, Nicolin Chen wrote:
> > > +static int arm_smmu_adopt_strtab_2lvl(struct arm_smmu_device *smmu, u32 cfg_reg,
> [..]
> > > +	cfg->l2.l1tab = devm_memremap(
> > > +		smmu->dev, dma, num_l1_ents * sizeof(struct arm_smmu_strtab_l1),
> > > +		MEMREMAP_WB);
> > 
> > WB shouldn't be unconditional? If the SMMU is working non-coherently
> > we need to map it NC. Same remark everwhere
> 
> Hmm, I am trying to add a coherent-only gate for the series.

OK, may just add a comment to that effect here

> MEMREMAP_WC might work. But we cannot verify that on a coherent
> SMMU, right?

At most you could fake the smmu to noncoherent and check it maps the
right thing and assume the arch code does it right

Jason